Method for manufacturing photomask and semiconductor thereof

ABSTRACT

A method for forming a photomask is provided. The method includes: receiving an initial layout including a plurality of first patterns and a plurality of second patterns; decomposing the initial layout into a first layout including the plurality of first patterns and a second layout including the plurality of second patterns; inserting a plurality of third patterns into the first layout, wherein each of the plurality of third patterns is adjacent to at least one of the plurality of first patterns; comparing the first layout and the second layout; identifying a fourth pattern as an overlapping portion of the plurality of third patterns overlapping one of the plurality of second patterns; increasing a width of the fourth pattern; and outputting the first layout including the first patterns, the third patterns and the fourth patterns into a first photomask.

BACKGROUND

A typical semiconductor manufacturing process includes numerous steps.Optical lithography is a crucial step in semiconductor manufacturing.The basic principle of optical lithography is quite similar to that offilm photography. The images of the patterned photomask are projectedthrough a high-precision optical lithography tool onto the wafersurface, which is coated with a layer formed of a light-sensitivechemical compound, e.g. photo-resist. Patterns are then formed on thewafer surface after complex chemical reactions and subsequentmanufacturing steps, such as development, post-exposure baking, and wetor dry etching.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the embodiments of the present disclosure are best understoodfrom the following detailed description when read with the accompanyingfigures. It should be noted that, in accordance with the standardpractice in the industry, various structures are not drawn to scale. Infact, the dimensions of the various structures may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 is a flowchart in accordance with some embodiments of the presentdisclosure.

FIGS. 2 to 7 are diagrams showing one or more operations of a method forforming a photomask in accordance with some embodiments of the presentdisclosure.

FIG. 8 is a cross-sectional view of a photomask in accordance with someembodiments of the present disclosure.

FIG. 9 is a diagram showing one or more operations of a method forforming a photomask in accordance with some embodiments of the presentdisclosure.

FIG. 10 is a cross-sectional view of a photomask in accordance with someembodiments of the present disclosure.

FIGS. 11 to 13 are diagrams showing one or more operations of a methodfor forming a photomask in accordance with some embodiments of thepresent disclosure.

FIGS. 14 to 15 are cross-sectional views of a photomask in accordancewith some embodiments of the present disclosure.

FIG. 16 is a diagram showing one or more operations of a method forforming a photomask in accordance with some embodiments of the presentdisclosure.

FIG. 17 is a cross-sectional view of a photomask in accordance with someembodiments of the present disclosure.

FIG. 18 is a flowchart in accordance with some embodiments of thepresent disclosure.

FIGS. 19 to 20 are diagrams showing one or more operations of asemiconductor manufacturing method in accordance with some embodimentsof the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of elements and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “over,” “upper,” “on” and the like, may be used herein for easeof description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. Thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly.

As used herein, the terms such as “first,” “second” and “third” describevarious elements, components, regions, layers and/or sections, but theseelements, components, regions, layers and/or sections should not belimited by these terms. These terms may be only used to distinguish oneelement, component, region, layer or section from another. The termssuch as “first,” “second” and “third” when used herein do not imply asequence or order unless clearly indicated by the context.

As used herein, the terms “approximately,” “substantially,”“substantial” and “about” are used to describe and account for smallvariations. When used in conjunction with an event or circumstance, theterms can refer to instances in which the event or circumstance occursprecisely as well as instances in which the event or circumstance occursto a close approximation. For example, when used in conjunction with anumerical value, the terms can refer to a range of variation of lessthan or equal to ±10% of that numerical value, such as less than orequal to ±5%, less than or equal to ±4%, less than or equal to ±3%, lessthan or equal to ±2%, less than or equal to ±1%, less than or equal to±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. Forexample, two numerical values can be deemed to be “substantially” thesame or equal if a difference between the values is less than or equalto ±10% of an average of the values, such as less than or equal to ±5%,less than or equal to ±4%, less than or equal to ±3%, less than or equalto ±2%, less than or equal to ±1%, less than or equal to ±0.5%, lessthan or equal to ±0.1%, or less than or equal to ±0.05%. For example,“substantially” parallel can refer to a range of angular variationrelative to 0° that is less than or equal to ±10°, such as less than orequal to ±5°, less than or equal to ±4°, less than or equal to ±3°, lessthan or equal to ±2°, less than or equal to ±1°, less than or equal to±0.5°, less than or equal to ±0.1°, or less than or equal to ±0.05°. Forexample, “substantially” perpendicular can refer to a range of angularvariation relative to 90° that is less than or equal to ±10°, such asless than or equal to ±5°, less than or equal to ±4°, less than or equalto ±3°, less than or equal to ±2°, less than or equal to ±1°, less thanor equal to ±0.5°, less than or equal to ±0.1°, or less than or equal to±0.05°.

The advanced lithography process, method, and materials described in thecurrent disclosure can be used in many applications, including fin-typefield effect transistors (FinFETs). For example, the fins may bepatterned to produce a relatively close spacing between features, forwhich the current disclosure is well suited. In addition, spacers usedin forming fins of FinFETs can be processed according to the currentdisclosure.

In order to enhance resolution and further decrease dimensions of asemiconductor device in semiconductor manufacturing, techniques oflayout decomposition are applied to develop an initial layout intoseveral layouts. One or more scattering bars are inserted to at leastone of the several layouts for producing a good lithographic result. Thescattering bar is not printable onto a photomask, and thus avoids waferdamage by lithographic process. This results in a constrained processwindow because the dimensions of the scattering bar are limited.

Some embodiments of the present disclosure provide a method for forminga photomask. The method according to some embodiments of the presentdisclosure includes operations to enlarge a dimension of at least aportion of a scattering bar of a decomposed layout. The enlargement ofthe scattering bar is intended to produce a good lithographic result dueto characteristics of optical diffraction. The enlargement is performedon a portion of the scattering bars that overlaps with other decomposedlayouts. When the initial layout is decomposed into at least twolayouts, at least a scattering bar is inserted into one of the at leasttwo layouts. The enlargement is performed on the portion of thescattering bar (or scattering bars) that overlaps patterns of anotherlayout, and thus the lithographic result can be enhanced due to anenlarged process window. No pattern is changed on a target layer of, forexample, a semiconductor wafer.

To illustrate concepts of the present disclosure, various embodimentswith the method applied are provided in the following description.However, such embodiments are not intended to limit the presentdisclosure.

As shown in FIG. 1, some embodiments of the present disclosure provide amethod M10 for forming a photomask. The method M10 includes: (O11)receiving an initial layout comprising a plurality of first patterns anda plurality of second patterns; (O12) separating the plurality of firstpatterns into a first layout and the plurality of second patterns into asecond layout; (O13) inserting a plurality of third patterns into thefirst layout, wherein each of the plurality of third patterns isadjacent to at least one of the plurality of first patterns; (O14)comparing the first layout and the second layout; (O15) identifying afourth pattern as an overlapping portion of the plurality of thirdpatterns overlapping one of the plurality of second patterns; (O16)increasing a width of the fourth patterns; and (O17) outputting thefirst layout comprising the first patterns, the third patterns and thefourth patterns into a first photomask.

In accordance with operation (O11) of the method M10 and someembodiments of the disclosure, referring to FIG. 2, an initial layoutOL1 is received. The initial layout OL1 includes a plurality of originalpatterns 10. The original patterns 10 are separated from each other byan original spacing distance D1. The original patterns 10 of the initiallayout OL1 include a plurality of first patterns 11 and a plurality ofsecond patterns 21. The first patterns 11 have a width W11 and a lengthL11, and the second patterns 21 have a width W21 and a length L21. Forease of illustration and understanding, in some embodiments of thepresent disclosure, the original spacing distances D1 between adjacentoriginal patterns 10 are the same, and each of the original patterns 10is a polygon. In some embodiments, each of the original patterns 10 isconfigured as a rectangle. In some embodiments, each of the firstpatterns 11 has the same configuration, and each of the second patterns21 has the same configuration, but the disclosure is not limitedthereto. In some embodiments, the width W21 of the second patterns 21 isgreater than the width W11 of the first patterns 11, but the disclosureis not limited thereto. In some embodiments, the length L21 of thesecond patterns 21 is approximately or substantially equal to (i.e., adifference between the values is less than or equal to ±10%) the lengthL11 of the first patterns 11. In some embodiments, the length L21 of thesecond patterns 21 is the same as the length L11 of the first patterns11.

In accordance with operation (O12) of the method M10 and someembodiments of the disclosure, referring to FIG. 2, the initial layoutOL1 is decomposed into a first layout DL11 and a second layout DL12 by adecomposition operation, which is also referred to as a coloringoperation. The plurality of first patterns 11 of the original patterns10 is separated into the first layout DL11, and the plurality of secondpatterns 21 of the original patterns 10 is separated into a secondlayout DL12. In other words, the plurality of original patterns 10 ofthe initial layout OL1 is decomposed into the plurality of firstpatterns 11 and the plurality of second patterns 21 of two differentlayouts DL11 and DL21. The first patterns 11 are separated from eachother by a spacing distance D11, and the second patterns are separatedfrom each other by a spacing distance D21. The spacing distance D21 ofthe second patterns 21 is greater than the original spacing distance D1.The spacing distance D11 of the first patterns 11 is greater than theoriginal spacing distance D1 and the second spacing distance D21. Insuch embodiments, the original layout OL1 is decomposed into two layoutsDL11 and DL12 that may be used to form patterns in a same layer, such asa metal layer or any other layer involved in the formation of integratedcircuits, such as a polysilicon layer. In some embodiments, an initiallayout is decomposed into more than two layouts.

The decomposition operation can be performed based on the originalspacing distance D1. To meet requirements of smaller dimensions andhigher resolution, the original spacing distance D1 can be smaller thana minimum distance of previous embodiments, thereby achieving aresolution that exceeds a resolution limit of existing opticallithography tools used to pattern or develop a target layer of asemiconductor wafer in a given semiconductor fabrication technologygeneration. The original spacing distance D1 can vary, depending onapplications and generations of semiconductor processing tools. However,once the original spacing distance D1 exceeds a default spacing distance(a default spacing distance also can vary, depending on the opticallithography tool used), the adjacent original patterns 10 are separatedinto different layouts for multiple-patterning operations. Thedecomposition operation can be repeatedly performed on the first layoutDL11 and the second layout DL12 until a spacing distance betweenadjacent patterns on the same layout is not smaller than the defaultspacing distance. However, in other embodiments, the initial patterns 10may be decomposed due to considerations other than tight spacing.

In accordance with operation (O13) of the method M10 and someembodiments of the disclosure, referring to FIG. 3, a plurality of thirdpatterns 13 are inserted into the first layout DL11, wherein each of theplurality of third patterns 13 is adjacent to at least one of theplurality of first patterns 11. In some embodiments, the third patterns13 are non-printable scattering bars. In some embodiments, a dimensionof the third patterns 13 is less than a dimension of the second patterns21 and a dimension of the first patterns 11. In some embodiments, thethird patterns 13 are inserted into a layout (formed afterdecomposition) having greater spacing distances between the patternsand/or smaller dimensions of the patterns as compared to other layouts.

For ease of illustration and understanding, the third patterns 13 arepolygonal, and in embodiments such as the embodiment shown in FIG. 3,the third patterns 13 are rectangles with same widths and same lengths,wherein the third patterns 13 have a length L13 and a width W13. Thewidth W13 of the third patterns 13 is less than the width W11 of thefirst patterns 11 and the width W21 of the second patterns 21. The thirdpatterns 13 are separated from each other by a spacing distance D13, andadjacent first and third patterns 11 and 13 are separated by a spacingdistance D131. In some embodiments, the third patterns 13 areindividually disposed between the first patterns 11 and separated fromthe first patterns 11 by the spacing distances D131, wherein the spacingdistances D131 are the same. The third patterns 13 are inserted forbalancing density of patterns within the first layout DL11 so thatisolated features to be formed can achieve performance comparable tothat of dense features to be formed. In some embodiments, diagrams ofthe first layout DL11 shown in the figures represent only a portion ofthe first layout DL11 having low density of the first patterns 11.

In accordance with operation (O14) of the method M10 and someembodiments of the disclosure, referring to FIG. 4, the first layoutDL11 is compared with the second layout DL12 after insertion of thethird patterns 13. FIG. 4 shows the second patterns 21 of the secondlayout DL12 in dotted lines overlaid on the first layout DL11 to showrelative positions of the first patterns 11, the second patterns 21 andthe third patterns 13 of the first layout DL11 and the second layoutDL12.

In accordance with operation (O15) of the method M10 and someembodiments of the disclosure, referring to FIG. 5, an overlappingportion of the plurality of third patterns 13 overlapping one of theplurality of second patterns 21 is identified as a fourth pattern 14. Inembodiments such as the embodiment shown in FIG. 5, the two thirdpatterns 13 on the left hand side overlap the second patterns 21 of thesecond layout DL12, and thus the two third patterns 13 are identified asthe fourth patterns 14. The fourth patterns 14 have a width W14 equal tothe width W13, and a spacing distance D14 between adjacent fourthpatterns 14 is equal to the spacing distance D13.

In accordance with operation (O16) of the method M10 and someembodiments of the disclosure, referring to FIG. 6, the width W14 of thefourth pattern 14 is increased to a width W14′. After the width W14 isincreased, the fourth pattern 14 entirely overlaps a correspondingsecond pattern 21 when the second layout DL12 overlaps the first layoutDL11, as shown in FIG. 6. The fourth pattern 14 having the width W14′ isentirely within a coverage area of the second pattern 21 when the secondlayout DL12 overlaps the first layout DL11.

In some embodiments, the fourth patterns 14 are printable scatteringbars. In some embodiments, the width W14′ of the fourth patterns 14 isapproximately or substantially equal to the first width W11 of the firstpatterns 11, wherein a difference between the values is less than orequal to ±10%. In some embodiments, the width W14′ of the fourthpatterns 14 is the same as the first width W11 of the first patterns 11.In some embodiments, a spacing distance D14′ between adjacent fourthpatterns 14 after a width increase is approximately or substantiallyequal to the first spacing distance D11 of the first patterns 11,wherein a difference between the values is less than or equal to ±10%.In some embodiments, the spacing distance D14′ of the fourth patterns 14after the width increase is the same as the first spacing distance D11of the first patterns 11. In some embodiments, spacing distances D141between the first patterns 11 and adjacent fourth patterns 14 having thewidth W14′ are substantially equal; that is, a difference between thevalues is less than or equal to ±10%. In some embodiments, the spacingdistances D141 between the fourth patterns 14 and adjacent firstpatterns 11 are the same. Thus, with the fourth patterns 14 and thefirst patterns 11, the first layout DL11 has more repetitive andperiodic patterns.

Moreover, the enlarged third patterns (i.e. the fourth patterns 14) alsoprovide a larger process window. In general, as is well known in theart, the term “process window” refers the amount of variation inexposure dose and focus which can be tolerated so that thecharacteristics of features (e.g., line width, wall angle, resistthickness) are maintained within prescribed specifications. Further, theusable focus range or depth of focus (DOF) typically refers to the rangeof focus settings wherein the lateral dimension of the feature or thespace between features lies within a prescribed specification of atargeted line width or critical dimension (CD). The process window canbe increased and the DOF can be improved by forming the fourth patterns14 having the width 14′ greater than the width 13 of the third patterns13.

In some embodiments, the third pattern 13 (e.g., a non-printablescattering bar) is separated from the fourth pattern 14 (e.g., aprintable scattering bar).

In accordance with operation (O17) of the method M10 and someembodiments of the disclosure, referring to FIG. 7, the first layoutDL11, including the first patterns 11, the third patterns 13 and thefourth patterns 14 having the width W14′, is outputted into a firstphotomask PM11. The first photomask PM11 includes a plurality ofpatterns 11′ corresponding to the first patterns 11, at least a pattern13′ corresponding to the third pattern 13, and a plurality of patterns14′ corresponding to the fourth patterns 14 of the first layout DL11.The first photomask PM11 is used, e.g. in a double-patterning operationor a multiple-patterning operation, to pattern a hard mask layer inorder to pattern a target layer of a semiconductor wafer. FIG. 8 shows across-sectional view of the first photomask PM11 along a line A-A′ inFIG. 7.

In accordance with some embodiments of the present invention, as shownin FIG. 9, the method M10 can further include operations of outputtingthe second layout DL12 into a second photomask PM12. The secondphotomask PM12 includes a plurality of patterns 21′ corresponding to thesecond patterns 21 of the second layout DL12. The second photomask PM12is used to pattern the hard mask layer in order to pattern the targetlayer of the semiconductor wafer, e.g. in a double-patterning operationor a multiple-patterning operation. FIG. 10 shows a cross-sectional viewof the second photomask PM12 along a line B-B′ in FIG. 9.

To further illustrate the concepts of the present disclosure, otherembodiments of the present disclosure are provided below following themethod M10 as illustrated above. In accordance with operation (O11) ofthe method M10 and some embodiments of the present disclosure, as shownin FIG. 11, an initial layout OL2 is received. Similar to the initiallayout OL1, the initial layout OL2 includes a plurality of originalpatterns 10. The original patterns 10 are separated from each other byan original spacing distance D1. The original patterns 10 of the initiallayout OL1 include a plurality of first patterns 11 and a plurality ofsecond patterns 21. The first patterns 11 have a width W11 and a lengthL11, and the second patterns 21 have a width W21 and a length L21. Forease of illustration and understanding, in some embodiments of thepresent disclosure, the original spacing distance D1 between adjacentoriginal patterns 10 are the same, and each of the original patterns 10is a rectangle. In some embodiments, all the first patterns 11 have thesame rectangular shape, and all the second patterns 21 have the samerectangular shape. As for the initial layout OL2, the width W21 of thesecond patterns 21 is greater than the width W11 of the first patterns11, and the length L21 of the second patterns 21 less than the lengthL11 of the first patterns 11.

It should be noted that, for ease of illustration and understanding, thenumeral references used in the initial layout OL2 are the same as thoseused in the initial layout OL1. Such numeral references are not intendedto limit different embodiments of the present disclosure into the sameelements. Repeated numeral references are used in layouts DL21 and DL22and photomasks PM21 and PM22 to represent different elements withsimilar or same functions or properties, but are not intended to limitthe present disclosure. In addition, in the following descriptions,illustrations of embodiments that are similar to the above embodimentsare omitted for brevity.

In accordance with operations (O12) to (O16) of the method M10 asillustrated above, fourth patterns 14 with increased widths W14′ of afirst layout DL21 are provided as shown in FIG. 12. Repeatedillustrations are omitted herein, but such omissions are not intended tolimit the present disclosure. Referring to FIG. 12, after the widthincrease, the fourth pattern 14 entirely overlaps the correspondingsecond patterns 21 when the second layout DL22 overlaps the first layoutDL21. The second patterns of the second layout DL22 are shown in dottedlines overlaid on the first layout DL21 to illustrate relative positionsof the first patterns 11, the second patterns 21, the third patterns 13and the fourth patterns 14 of the first layout DL21 and the secondlayout DL22. The fourth pattern 14 having the width W14′ is entirelywithin a coverage area of the second pattern 21 when the second layoutDL22 overlaps the first layout DL21.

In some embodiments, a length L14′ of the fourth patterns 14 is lessthan a length L13 of the third patterns 13 and the length L11 of thefirst patterns 11. In some embodiments, relationships of the width W14′and the first width W11 of the first layout DL21 are similar torelationships of the width W14′ and the first width W11 of the firstlayout DL11. In some embodiments, relationships of a spacing distanceD14′ and the first spacing distance D1 of the first layout DL21 aresimilar to relationships of the spacing distance D14′ and the firstspacing distance D11 of the first layout DL11. In some embodiments,spacing distances D141 between the first patterns 11 and adjacent fourthpatterns 14 having the width W14′ are substantially equal, wherein adifference between the values is less than or equal to ±10%. In someembodiments, the spacing distances D141 between the fourth patterns 14and adjacent first patterns 11 are the same. Thus, with the fourthpatterns 14 and the first patterns 11, the first layout DL21 can havemore repetitive, and periodic patterns.

In some embodiments, the third patterns 13 are non-printable scatteringbars, and the fourth patterns 14 are printable scattering bars. In someembodiments, at least a portion of the third patterns 13 are coupledwith or in contact with the fourth patterns 14. In some embodiments, atleast a portion of third patterns 13 (e.g., the third pattern 13 on theright side of FIG. 12) are separated from the fourth patterns 14.

In accordance with operation (O17) of the method M10 and someembodiments of the disclosure, referring to FIG. 13, the first layoutDL21, including the first patterns 11, the third patterns 13, and thefourth patterns 14 having the width W14′ are outputted into a firstphotomask PM21. The first photomask PM21 includes a plurality ofpatterns 11′ corresponding to the first patterns 11, a plurality ofpatterns 13′ corresponding to the third patterns 13, and a plurality ofpatterns 14′ corresponding to the fourth patterns 14 of the first layoutDL21. The first photomask PM21 is used, e.g. in a double-patterningoperation or a multiple-patterning operation, to pattern a hard masklayer in order to pattern a target layer of a semiconductor wafer. FIGS.14 and 15 show cross-sectional views of the first photomask PM21 along aline C-C′ and a line D-D′ in FIG. 13 respectively.

In accordance with some embodiments of the present invention, as shownin FIG. 16, the method M10 can further includes operations of outputtingthe second layout DL22 into a second photomask PM22. The secondphotomask PM22 includes a plurality of patterns 21′ corresponding to thesecond patterns 21 of the second layout DL12. The second photomask PM22is used to pattern the hard mask layer in order to pattern the targetlayer of the semiconductor wafer, e.g. in a double-patterning operationor a multiple-patterning operation. FIG. 17 shows a cross-sectional viewof the second photomask PM22 along a line E-E′ in FIG. 16.

In some embodiments of the present disclosure, a double-patterningoperation can be performed using the above-illustrated first photomaskPM11 and second photomask PM12 to apply desired patterns onto a hardmask layer or a target layer of a semiconductor wafer. In the followingdescription, for ease of illustration and understanding, similar or sameelements with similar or same functions or properties use the samenumeral references repeatedly, but such use of same numeral referencesis not intended to limit the present disclosure. In the followingillustrated embodiments, the fourth patterns can be represented as first(or printable) scattering bars, and the third patterns can berepresented as second (or non-printable) scattering bars.

Some embodiments of the present disclosure provide a semiconductormanufacturing method M20. Referring to FIG. 18, the semiconductormanufacturing method M20 includes operations of: (O21) receiving a firstphotomask including a first pattern and a first scattering bar; (O22)using the first photomask to remove a first portion of a target layer toform a first opening corresponding to the first pattern and a secondopening corresponding to the first scattering bar; (O23) receiving asecond photomask including a second pattern; and (O24) using the secondphotomask to remove a second portion of the target layer to form a thirdopening corresponding to the second pattern, wherein the second openingis widened to form the third opening using the second photomask.

In accordance with operation (O21) of the method M20 and someembodiments of the present disclosure, referring to FIG. 19, the firstphotomask PM11 is received. In accordance with some embodiments, thefirst photomask PM11 includes a plurality of first patterns 11′, aplurality of first scattering bars 14′, and a second scattering bar 13′,wherein the first scattering bars 14′ are printable onto a photoresistlayer, and the second scattering bar 13′ is not printable onto aphotoresist layer.

Referring to FIG. 19, a substrate including a material layer TM1 and atarget layer TL1 disposed on the material layer TM1 is received. Thematerial layer TM1 can be a semiconductor material layer or asemiconductor wafer. In accordance with operation (O22) of the methodM20, the first photomask PM11 is used to remove a first portion of thetarget layer TL1 to form a first opening OP1 corresponding to the firstpattern 11′ and a second opening OP2 corresponding to the firstscattering bar 14′. As shown in FIG. 19, a photoresist layer is formedon the target layer TL. The first photomask PM11 is transferred onto thephotoresist layer; in other words, the first patterns 11′ and the firstscattering bars 14′ are transferred to the photoresist layer PR1 to forma patterned photoresist layer PR1. The patterned photoresist layer PR1includes a plurality of openings corresponding to the first patterns 11′and the first scattering bars 14′. The patterned photoresist layer PR1is used as a mask to remove the first portion of the target layer TL1 inorder to transfer the first patterns 11′ and the first scattering bars14′ onto the target layer TL1, e.g. by etching operations. The targetlayer TL1 including the first openings OP1 and the second openings OP2is formed. The patterned photoresist layer PR1 is removed.

In accordance with operations (O23) to (O24) of the method M20 and someembodiments of the present disclosure, referring to FIG. 20, the secondphotomask PM12 is received. The second photomask PM12 includes at leasta second pattern 21′. The second photomask PM12 is used to remove asecond portion of the target layer TL1 to form a third opening OP3corresponding to the second pattern 21′. As shown in FIG. 20, aphotoresist layer is formed on the target layer TL1 after formation ofthe first openings OP1 and the second openings OP2, and optionally afterremoval of the photoresist PR1. The second photomask PM12 is transferredonto the photoresist layer; in other words, the second patterns 21′ aretransferred onto the photoresist layer to form a patterned photoresistlayer PR2. The patterned photoresist layer PR2 includes a plurality ofopenings corresponding to the second patterns 21′. The patternedphotoresist layer PR2 is used as a mask to remove the first portion ofthe target layer TL1 in order to transfer the second patterns 21′ ontothe target layer TL1, e.g. by etching operations. The third openings OP3corresponding to the second patterns 21′ are formed on the target layerTL1, wherein the second openings OP2 are widened to become the thirdopenings OP3. As illustrated above in the method M10 for forming aphotomask, the fourth patterns 14′ totally overlap the second patterns21, and thus the second opening OP2 is within a coverage area of thethird opening OP3. The target layer TL1, including the third openingsOP3 corresponding to the second patterns 21 and the first openings OP1corresponding to the first patterns 11′, is formed. The patternedphotoresist layer PR2 is removed.

FIGS. 19 to 20 show cross-sectional views of the first photomask PM11and the second photomask PM12. A top view of the first photomask PM11 isshown in FIG. 7. The first photomask PM11 can also include a secondscattering bar 13′. In some embodiments, a width W13′ of the secondscattering bar 13′ is less than a width W14″ of the first scatteringbars 14′ and a width W11′ of the first patterns 11′. In some embodimentsof the first photomask PM11, the first scattering bar 14′ and the secondscattering bar 13′ are separated. In some embodiments of the firstphotomask PM21, the first scattering bar 14′ is coupled to the secondscattering bar 13′ (connected or in contact).

Some embodiments of the present disclosure provide a photomask includingboth non-printable scattering bars and printable scattering bars. Usingthe first photomask PM21 as shown in FIGS. 13 to 15 for illustration,the photomask PM21 includes a first pattern 11′, a printable scatteringbar 14′, and a non-printable scattering bar 13′. The first pattern 11′has a width W11′. The printable scattering bar 14′ is adjacent to thefirst pattern 11′, and has a width W14″. The non-printable scatteringbar 13′ is adjacent to the first patterns 11′, and has a width W11′. Thewidth WI 1′ of the first pattern 11 and the width W14″ of the printablescattering bar 14′ are both greater than the width W13′ of thenon-printable scattering bar 13′. A spacing distance D141′ between thefirst pattern 11′ and the printable scattering bar 14′ is less than orequal to a spacing distance D131′ between the first pattern 11′ and thenon-printable scattering bar 13′. In some embodiments, the printablescattering bar 14′ and the non-printable scattering bar 13′ are coupled.In some embodiments, the printable scattering bar 14′ and thenon-printable scattering bar 13′ are separated from each other by thefirst pattern 11′.

Some embodiments of the present disclosure provide a method for forminga photomask. The method includes: receiving an initial layout includinga plurality of first patterns and a plurality of second patterns;decomposing the initial layout into a first layout including theplurality of first patterns and a second layout including the pluralityof second patterns; inserting a plurality of third patterns into thefirst layout, wherein each of the plurality of third patterns isadjacent to at least one of the plurality of first patterns; comparingthe first layout and the second layout; identifying a fourth pattern asan overlapping portion of the plurality of third patterns overlappingone of the plurality of second patterns; increasing a width of thefourth pattern; and outputting the first layout including the firstpatterns, the third patterns and the fourth patterns into a firstphotomask.

Some embodiments of the present disclosure provide a semiconductormanufacturing method. The semiconductor manufacturing method includes:receiving a first photomask including a first pattern and a firstscattering bar; using the first photomask to remove a first portion of atarget layer to form a first opening corresponding to the first patternand a second opening corresponding to the first scattering bar;receiving a second photomask including a second pattern; and using thesecond photomask to remove a second portion of the target layer to forma third opening corresponding to the second pattern, wherein the secondopening is widened to form the third opening using the second photomask.

Some embodiments of the present disclosure provide a photomask. Thephotomask includes a first pattern, having a first width; a printablescattering bar, adjacent to the first pattern, and having a secondwidth; and a non-printable scattering bar, adjacent to the first patternand having a third width, wherein the first width of the first patternand the second width of the printable scattering bar are greater thanthe third width of the non-printable scattering bar, and a spacingdistance between the first pattern and the printable scattering bar isless than or equal to a spacing distance between the first pattern andthe non-printable scattering bar.

The foregoing outlines structures of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for forming a photomask, comprising:receiving an initial layout comprising a plurality of first patterns anda plurality of second patterns; decomposing the initial layout into afirst layout including the plurality of first patterns and a secondlayout including the plurality of second patterns; inserting a pluralityof third patterns into the first layout, wherein each of the pluralityof third patterns is adjacent to at least one of the plurality of firstpatterns; comparing the first layout and the second layout; identifyinga fourth pattern as an overlapping portion of the plurality of thirdpatterns overlapping one of the plurality of second patterns; increasinga width of the fourth pattern; and outputting the first layoutcomprising the first patterns, the third patterns and the fourthpatterns into a first photomask.
 2. The method of claim 1, furthercomprising: receiving the initial layout comprising a plurality oforiginal patterns, wherein the plurality of original patterns areseparated from each other by an original spacing distance; anddecomposing the plurality of original patterns into the plurality offirst patterns and the plurality of second patterns, wherein theplurality of first patterns are separated from each other by a firstspacing distance and the plurality of second patterns are separated fromeach other by a second spacing distance.
 3. The method of claim 2,wherein the first spacing distance and the second spacing distance aregreater than the original spacing distance.
 4. The method of claim 1,wherein a length of the fourth pattern is similar to a length of theplurality of the third patterns.
 5. The method of claim 1, wherein alength of the fourth pattern is less than a length of the plurality ofthird patterns.
 6. The method of claim 1, wherein the plurality of firstpatterns have a first width, the plurality of second patterns have asecond width, and the plurality of third patterns have a third widthless than the first width and the second width.
 7. The method of claim6, wherein the width of the fourth pattern is increased to a fourthwidth, and the fourth width of the fourth pattern is similar to thefirst width.
 8. The method of claim 1, wherein after the increasing ofthe width, the fourth pattern entirely overlaps one of the plurality ofsecond patterns.
 9. The method of claim 1, further comprising:outputting the second layout into a second photomask.
 10. Asemiconductor manufacturing method, comprising: receiving a firstphotomask including a first pattern and a first scattering bar; usingthe first photomask to remove a first portion of a target layer to forma first opening corresponding to the first pattern and a second openingcorresponding to the first scattering bar; receiving a second photomaskincluding a second pattern; and using the second photomask to remove asecond portion of the target layer to form a third opening correspondingto the second pattern, wherein the second opening is widened to form thethird opening using the second photomask.
 11. The method of claim 10,wherein the first photomask further includes a second scattering bar.12. The method of claim 11, wherein a width of the second scattering baris less than a width of the first scattering bar and a width of thefirst pattern.
 13. The method of claim 11, wherein the second scatteringbar is non-printable.
 14. The method of claim 11, wherein the firstscattering bar and the second scattering bar are separated.
 15. Themethod of claim 12, wherein the first scattering bar and the secondscattering bar are coupled.
 16. The method of claim 10, wherein usingthe first photomask to remove the first portion of the target layercomprises: forming a first photoresist layer on the target layer;transferring the first pattern and the first scattering bar to the firstphotoresist layer to form a patterned first photoresist layer; andetching the target layer through the patterned first photoresist layerto form the target layer including the first opening and the secondopening.
 17. The method of claim 16, wherein using the second photomaskto remove a second portion of the target layer comprises: forming asecond photoresist layer on the target layer including the first openingand the second opening; transferring the second pattern to the secondphotoresist layer to form a patterned second photoresist layer; andetching the target through the patterned second photoresist layer toform the third opening on the target layer, wherein the second openingis widened to become the third opening.
 18. A photomask, comprising: afirst pattern, having a first width; a printable scattering bar,adjacent to the first pattern, and having a second width; and anon-printable scattering bar, adjacent to the first pattern and having athird width, wherein the first width of the first pattern and the secondwidth of the printable scattering bar are greater than the third widthof the non-printable scattering bar, and a spacing distance between thefirst pattern and the printable scattering bar is less than or equal toa spacing distance between the first pattern and the non-printablescattering bar.
 19. The photomask of claim 18, wherein the printablescattering bar and the non-printable scattering bar are coupled.
 20. Thephotomask of claim 18, wherein the printable scattering bar and thenon-printable scattering bar are separated from each other by the firstpattern.